If the Baltimore Ravens defense is to maintain its unwavering standard of excellence in 2012, the unit must mesh with a new coordinator and operate without several key components — most notably injured All-Pro linebacker Terrell Suggs.

Troy Polamalu’s strained right Achilles’ tendon isn’t allowing him to practice most weeks. The Steelers don’t want to take the chance that one of the NFL’s most valuable defensive players will aggravate the injury and won’t be able to play.